This invention relates to a bearing device of a boundary layer of pressurized air type, which provides a semi-cylindrical surface, on which a rotary shaft may be supported with the aid of pressurized air, and more particularly to a bearing device for use with a main shaft in a wire-twisting machine.
Heretofore, many types of bearings, such as ball bearings, have been used as bearing devices for shafts. However, the prior art bearings cause excessive noise in the case of high speed rotation of a shaft and increased driving power, due to the friction of a bearing portion.
One attempt to eliminate bearing noise is to use a gas type bearing, in which a pressurized gas (e.g. air) is introduced for circulation through a bore provided in a shaft. However, such bearings have suffered from the disadvantages of complexity in construction and high manufacturing cost.
It is also known to provide an annular type bearing using pressurized gas which is injected through the annular surface. If gas is injected through an upper annular member of a bearing, then a pressurized gas should also be injected from below to obtain an equilibrium for a main shaft. A difference between the downward and upward pressures exerted on the main shaft results in a complicated design and construction of a bearing device.